What is the "Democratic Wing"?

Dave Johnson of Seeing The Forest has some good comments on this issue:
Being in the Democratic wing is about being an opposition party and standing up for the people of the country and the interests of the nation instead of cowering before the Bush intimidation machine, allowing the right to persue their radical agenda to take the country back to the 19th century. That's what it's about, not about being a leftie. And it's about getting it. Checking in with weblogs is getting it. Reading BuzzFlash is getting it. Understanding what the grassroots are talking about is getting it. THAT is why Governor Howard Dean is doing so well with the grassroots, and THAT is why Dean can use the phrase "from the Democratic wing of the Democratic Party."
I've been trying to point this out as well. I'm hearing comments from the left that Dean shouldn't use this phrase because he isn't as far to the left as Paul Wellstone was. I'm also hearing comments from the right that Dean's use of the phrase proves that he IS as far to the left as Paul Wellstone was. But Dave puts them right when he says that being from the Democratic wing means acting like a Democrat, not a lighter version of a Republican. It means distinguishing yourself from the opposition. It means acting like you actually are the opposition. That is what has been missing from the Democratic party and it is what Dean is bringing back to the party: a sense of purpose.